The demand for good x is estimated to be: Qxᵈ = 10,000 - 4Px - 5PY + 2M + Ax, where Px is the price of x, PY is the price of good Y, M is income, and Ax is the amount of advertising on x. Suppose the present price of good x is $50, PY = $100, M = $25,000, and Ax = 1,000 units. Based on this information, the cross-price elasticity between goods x and Y is:
A. 0.008.
B. -0.082.
C. -0.816.
D. -8.157.